Seat lifting devices

ABSTRACT

Seat lifting devices disposed between a seat support for supporting a seat cushion and a seat mount for mounting the seat support in order to vertically adjust the seat cushion are taught that comprise a first linking mechanism movably interconnecting the seat support and the seat mount. The first linking mechanism comprises first and second linking arms that are respectively pivotally connected to the seat mount and the seat support via pivot axes. One of the pivot axes of the second linking arm comprises a movable pivot axis that is arranged and constructed to move along the second linking arm and to engage the second linking arm, so that substantial length of the second linking arm can be changed when the movable pivot axis moves along the second linking arm.

[0001] This application claims priority to Japanese Patent ApplicationSerial Number 2002-150970, the contents of which are incorporated hereinby reference.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to seat vertical devices or seatlifting devices for adjusting height of a seat cushion of a vehicleseat.

[0004] 2. Description of the Related Art

[0005] A seat vertical device or seat lifting device for adjustingheight of a seat cushion of a vehicle seat is taught, for example, byU.S. Pat. No. 6,347,778 and Japanese Laid-Open Patent Publication No.2001-163091.

[0006] Typically, a vehicle seat comprises a seat back and a seatcushion. The seat back and the seat cushion are respectively supportedby a seat back frame and a cushion frame. The cushion frame includes apair of opposing elongated plate-shaped members or frame elements. Thecushion frame thus constructed is seated on a seat slide device that aredisposed on a vehicle floor. The seat slide device has a pair of sliderail assemblies that are arranged in parallel each other. The slide railassemblies are positioned such that the distance therebetween issubstantially identical to the distance between the frame elements ofthe cushion frame. Each of the slide rail assemblies includes an upperrail and a lower rail. The lower rail is affixed to the vehicle floor.The upper rail slidably engages the affixed lower rail.

[0007] In the known art described in U.S. Pat. No. 6,347,778, each ofthe frame elements of the cushion frame is linked to the upper rail ofthe slide rail assembly via front and rear linking mechanisms, whichmechanisms constitute a seat lifting device. The front and rear linkingmechanisms respectively include a front bracket and a rear bracket thatare upwardly projected from the upper rail. The front linking mechanismfurther includes a front arm, which arm is pivotally attached to theframe element and the front bracket via pivot pins. Similarly, the rearlinking mechanism further includes a rear arm, which arm is pivotallyattached to the frame element and the rear bracket via pivot pins.

[0008] Further, the seat lifting device includes a drive mechanism,which drive mechanism also constitutes the seat lifting device. Thedrive mechanism includes a lever, an intermediate bracket upwardlyproject from the upper rail and a linking rod. The lever is pivotallyattached to the intermediate bracket in its middle portion. One end ofthe linking rod is pivotally connected to the rear arm. Also, the otherend of the linking rod is pivotally connected to an upper end of thelever. Further, a nut is rotatably attached to a lower end of the lever.This nut threadably engages a threaded shaft that is driven or rotatedby a drive means or motor. Therefore, when the threaded shaft is rotatedby the motor, the nut moves along the threaded shaft, thereby pivotingthe lever around the intermediate bracket. As a result, the linking rodconnected to the lever moves back and forth, thereby pivoting the reararm. Thus, the flame element can be lifted, so that the height of thevehicle seat cushion can be adjusted.

[0009] In the known seat lifting device, the rear arm is formed with alaterally elongated slot (first slot) and a vertically elongated arcuateslot (second slot) having a plurality of concave portions arrangedtherealong. On the other hand, the rear arm is provided with a pivot pinthat is received in the first slot and a locking pin that is received inthe second slot.

[0010] According to the known seat lifting device, when an excessiveforward and upward force is applied to the cushion frame via a seatbeltthat is attached thereto, each of the frame elements of the cushionframe may be pulled forwardly and upwardly and moves in this direction.As a result, the rear arm rotates around the pivot pin. However, becausethe pivot pin is received within the elongated slot, the rear armforwardly is shifted, thereby engaging the locking pin with one of theconcave portions of the second slot. Thus, the seat lifting device islocked, thereby preventing the frame element from further movingforwardly and upwardly. As a result, the rear arm can be effectivelyprevented from further rotating around the pivot pin. Therefore, thedrive mechanism that is linked to the rear arm can be effectivelyprevented from being subjected to an undesirable large force.

[0011] As will be recognized, if the seat lifting device is not lockedwhen the excessive forward and upward force is applied to the cushionframe, the frame element cannot be prevented from moving forwardly andupwardly. Therefore, the rear arm can freely rotate around the pivotpin. As a result, a considerable force may be applied to the drivemechanism linked to the rear arm. Such a force may exert undesirableeffects on the drive mechanism.

SUMMARY OF THE INVENTION

[0012] It is, accordingly, one object of the present teachings toprovide improved seat lifting devices for adjusting height of a seatcushion of a vehicle seat.

[0013] For example, in one aspect of the present teachings, seat liftingdevices disposed between a seat support for supporting a seat cushionand a seat mount for mounting the seat support in order to verticallyadjust the seat cushion are taught that comprises a first linkingmechanism movably interconnecting the seat support and the seat mount.The first linking mechanism comprises first and second linking arms thatare respectively pivotally connected to the seat mount and the seatsupport via pivot axes. One of the pivot axes of the second linking armcomprises a movable pivot axis that is arranged and constructed to movealong the second linking arm and to engage the second linking arm, sothat substantial length of the second linking arm can be changed whenthe movable pivot axis moves along the second linking arm.

[0014] In such seat lifting devices, the movable pivot axis engages thesecond linking arm. Therefore, even if an excessive forward force isapplied to the seat support, the first linking mechanism may reliably beimmobilized, thereby locking the seat lifting device. As a result, theseat support may substantially be prevented from moving.

[0015] Other objects, features and advantage of the present inventionwill be ready understood after reading the following detaileddescription together with the accompanying drawings and the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016]FIG. 1 is a side view illustrating a vehicle seat having a seatlifting device according to a first embodiment of the present teachings,in which the vehicle seat is adjusted to a lowered position;

[0017]FIG. 2 is a side view illustrating the vehicle seat, in which thevehicle seat is adjusted to a lifted position;

[0018]FIG. 3 is an exploded partially perspective view of the seatlifting device disposed on a upper rail of a seat slide device;

[0019]FIG. 4 is a side view similar to FIG. 1, which view illustrates avehicle seat having a seat lifting device according to a secondembodiment of the present teachings; and

[0020]FIG. 5 is an exploded partially perspective view of the seatlifting device disposed on a upper rail of a seat slide device; and

[0021]FIG. 6 is a side view similar to FIG. 1, which view illustrates avehicle seat having a seat lifting device according to a thirdembodiment of the present teachings.

DETAILED DESCRIPTION OF THE INVENTION

[0022] In one embodiment of the present teachings, seat lifting devicesdisposed between a cushion frame for supporting a seat cushion and aseat slide device for mounting the cushion frame in order to verticallyadjust the seat cushion may comprises a rear linking mechanism movablyinterconnecting the cushion frame and the seat slide device. The rearlinking mechanism comprises first and second linking arms that arerespectively pivotally connected to the seat slide device and thecushion frame via pivot axes. One of the pivot axes of the secondlinking arm comprises a movable pivot axis that is arranged andconstructed to move along the second linking arm and to engage thesecond linking arm, so that substantial length of the second linking armcan be changed when the movable pivot axis moves along the secondlinking arm.

[0023] Optionally, the second linking arm may comprise a threaded shaftthat is pivotally connected to the seat slide device and the cushionframe and a gear assembly that engages the threaded shaft. Preferably,the gear assembly may be arranged and constructed to move along thethreaded shaft. Preferably, the movable pivot axis may be mechanicallyconnected to the gear assembly, so as to move along the threaded shaftwhen the gear assembly moves along the threaded shaft.

[0024] Optionally, the seat lifting devices may further comprise asecond linking mechanism movably interconnecting the cushion frame andthe seat slide device. The second linking mechanism may comprise anelongated guide slot formed in the seat slide device and a guide pinattached to the cushion frame. The guide pin may slidably engage theguide slot.

[0025] Further, the seat lifting devices may further comprises anactuator. The actuator may preferably be arranged and constructed todrive the gear assembly, thereby relatively moving the gear assembly andthe movable pivot axis attached thereto along the threaded shaft.

[0026] Optionally, the first and second linking arms may preferably beconnected to the cushion frame via a common pivot axis. Further, thefirst and second linking arms may respectively be connected to the seatslide device via first and second pivot axes. The second pivot axis maypreferably be positioned behind the first pivot axis.

[0027] Preferably, the first linking mechanism may be positionedadjacent to a seatbelt connecting position on the seat support.

[0028] Two detailed representative embodiments of the present teachingswill now be described in further detail with reference to FIGS. 1 to 5.

[0029] First Detailed Representative Embodiment

[0030] The first detailed representative embodiment will now bedescribed with reference to FIGS. 1 to 3.

[0031] As shown in FIGS. 1 and 2, a vehicle seat 1 of this embodimentgenerally comprises a seat back 4 and a seat cushion 10. The seat back 4and the seat cushion 10 are respectively supported by a seat back frame2 and a cushion frame (i.e., seat support) 8. Typically, the cushionframe 8 includes a pair of opposing elongated plate-shaped members orframe elements 12 (one of which is shown) and a connector member (notshown). Each of the frame elements 12 has a front portion 12 a and arear portion 12 b. The rear portions 12 b of the frame elements 12 areinterconnected by the connector member, thereby defining the cushionframe 8 as a unit. In addition, a seatbelt 18 may preferably connectedto the frame elements 12 via seatbelt connectors (not shown) that arepositioned adjacent to the rear portions 12 b.

[0032] The cushion frame 8 thus constructed is seated on a pair of sliderail assemblies 3 (one of which is shown) of a seat slide device (i.e.,seat mount) that are disposed in parallel on a vehicle floor (notshown). The slide rail assemblies 3 may be positioned such that thedistance therebetween is substantially identical to the distance betweenthe frame elements 12 of the cushion frame 8. Each of the slide railassemblies 3 may include an upper rail 16 and a lower rail 14. The lowerrail 14 may be affixed to the vehicle floor. The upper rail 16 slidablyengages the affixed lower rail 14. In addition, the frame elements 12 ofthe cushion frame 8 are linked to the upper rails 16 via a pair of firstor rear linking mechanisms 30 (one of which is shown) and a pair ofsecond or front linking mechanisms 20 (one of which is shown), whichmechanisms constitute a seat lifting device. Thus, the cushion frame 8may preferably be operatively connected to the slide rail assemblies 16.

[0033] The cushion frame 8 can be moved back and forth by sliding theupper rail 16 back and forth along the lower rail 14. Therefore, thelongitudinal position of the seat cushion 10 can be adjusted by slidingthe upper rail 16 along the lower rail 14. In addition, the cushionframe 8 can be moved up and down by operating the seat lifting device.Therefore, the vertical position of the seat cushion 8 can be adjustedby operating the seat lifting device.

[0034] As shown in FIGS. 1 to 3, each of the front linking mechanisms 20of the seat lifting device may preferably include a guide bracket 22that is fixed to an upper surface 16 a of the upper rail 16. The guidebracket 22 is formed with an elongated arcuate guide slot 22 a that isvertically extended and fowardly curved with respect to the upper rail16. Further, the front linking mechanism 20 may include a guide pin 24that is attached to the front portion 12 a of the frame element 12. Theguide pin 24 slidably engages the guide slot 22 a such that the frontportion 12 a of the frame element 12 can move vertically andlongitudinally with respect to the upper rail 16 along an arcuate paththat is defined by the guide slot 22 a.

[0035] As best shown in FIG. 3, each of the rear linking mechanisms 30of the seat lifting device may include a plate-shaped linking arm (i.e.,first linking arm) 36. Further, the rear linking mechanism 30 maypreferably include a first or pivot bracket 32 and a second or supportbracket 34 that are fixed to the upper surface 16 a of the upper rail16. An upper end of the linking arm 36 is pivotally connected to therear portion 12 b of the frame element 12 via a pivot axis or pivot pin38 such that the arm 36 can pivot back and forth around the pivot pin38. A lower end of the linking arm 36 is pivotally connected to thesupport bracket 34 via a first pivot axis or pivot pin 39 such that thearm 36 can pivot back and forth around the pivot pin 39.

[0036] Also, the rear linking mechanism 30 may preferably include aretainer 48 that is fixedly connected to the rear portion 12 b of theframe element 12 by appropriate fixing means. In this embodiment, theretainer 48 is fixed to the frame element rear portion 12 b by engagingapertures 48 a formed in the retainer 48 with fixture pins 52 providedto the rear portion 12 b and then caulking the fixture pins 52 orattaching E-rings (not shown) to the fixture pins 52.

[0037] Further, the fixing means of the retainer 48 is not limited tothis embodiment. For example, the retainer 48 can be fixed to the frameelement rear portion 12 b by utilizing apertures (not shown) formed inthe retainer 48 and the rear portion 12 b and bolts (not shown) and nuts(not shown).

[0038] As best shown in FIG. 3, the seat lifting device may furtherinclude a pair of drive mechanisms 40 (one of which is shown). Each ofthe drive mechanisms 40 may preferably includes a drive source assemblythat comprises a gear box 44 and an actuator or motor 42. The gear box44 and the motor 42 may preferably be vertically positioned. The motor42 is combined to the gear box 44 such that a drive gear (not shown)received in the gear box 44 is driven when the motor 42 is driven. Inaddition, the gear box 44 has a threaded shaft (i.e., second linkingarm) 46 extending therethrough. As will be appreciated, the threadedshaft 46 threadably engages the drive gear received in the gear box 44such that the gear box 44 moves along the threaded shaft 46 when themotor 42 is forwardly or reversely driven.

[0039] As shown in FIG. 3, the gear box 44 is movably or rotatablyconnected to the retainer 48 via a pivot axis or pivot pin 50.Therefore, the pivot pin 50 can move along the threaded shaft 46 whenthe gear box 44 moves along the threaded shaft 46. Further, the pivotpin 50 may preferably be aligned with the pivot pin 38 of the linkingarm 36. As a result, the gear box 44 and the upper end of the linkingarm 36 are connected to the rear portion 12 b of the frame element 12via a common pivot axis. Further, the threaded shaft 46 has an aperture46 a that is formed in its rear end. The rear end of the threaded shaft46 is pivotally connected to the support bracket 34 via a second pivotaxis or pivot pin 54 received in the aperture 46 a such that thethreaded shaft 46 can pivot back and forth around the pivot pin 54. Aswill be appreciated, the gear box 44 and the threaded shaft 46 mayfunction as a part of the rear linking mechanism 30. In other words, thegear box 44 and the threaded shaft 46 may preferably constitute both ofthe drive mechanism 40 and the rear linking mechanism 30.

[0040] Further, the pivot pins 38 and 50 is not limited to thisembodiment. For example, the pivot pin 38 can be extended along alongitudinal axis thereof, so that the gear box 44 can be pivotallyconnected to the retainer 48 via an extended end of the pivot pin 38.According to this construction, the pivot pin 50 can be omitted.

[0041] According to the seat lifting device of this embodiment, wheneach of the drive mechanisms 40 is actuated, the front and rear linkingmechanisms 20 and 30 of the seat lifting device are operated, therebychanging height of the seat cushion 10. That is, when the motor 42 ofthe drive mechanism 40 is driven forwardly or reversely, the gear box 44moves forwardly or backwardly along the threaded shaft 46, therebychanging substantial length of the threaded shaft 46. As a result, thepivot pins 38 and 50 of the rear linking mechanisms 30 moves verticallyand longitudinally relative to the upper rail 16 while the linking arm36 and the threaded shaft 46 respectively pivotally rotate around thepivot pin 39 and the pivot pin 54. At this time, the guide pin 24 of thefront linking mechanism 20 synchronously moves along the guide slot 22 aof the guide bracket 22. Consequently, the front and rear linkingmechanisms 20 and 30 simultaneously rise or fall down. Therefore, theframe elements 12 linked to the linking mechanisms 20 and 30 are shiftedupwardly or downwardly. Thus, the seat cushion 10 may preferably becontinuously vertically adjusted, so as to have various verticalpositions (e.g., a lowered position (FIG. 1) and a lifted position (FIG.2)).

[0042] According to the seat lifting device of this embodiment, when anexcessive forward force is applied to the cushion frame 8 via theseatbelt 18 that is attached thereto, each of the frame elements 12 ofthe cushion frame 8 is pulled forwardly and upwardly. As a result, thefront and rear linking mechanisms 20 and 30 that is linked to the frameelement 12 are pulled in this direction. However, because the drive gearreceived in the gear box 44 threadably engages the threaded shaft 46,the rear linking mechanism 30 may preferably be immobilized, therebylocking the seat lifting device. As a result, the frame element 12 maybe substantially prevented from moving forwardly and upwardly. That is,the seat cushion 10 may be prevented from moving forwardly and upwardly.Therefore, the drive mechanism 40, for example, may be prevented frombeing applied with a considerable large force.

[0043] In this embodiment, the seat lifting device is always lockedunless the drive mechanisms 40 is actuated. As a result, even if theexcessive forward force is applied to the cushion frame 8, the frameelement 12 can be maintained in place without moving forwardly andupwardly. Therefore, the drive mechanism 40 can be reliably preventedfrom being applied with such a considerable force.

[0044] Further, in this embodiment, the gear box 44 and the threadedshaft 46 of the drive mechanism 40 constitute a part of the rear linkingmechanism 30. Therefore, the seat lifting device can be simplified.

[0045] Further, the seat lifting device is not limited to therepresentative embodiment. For example, the front linking mechanism 20may include a linking arm that is pivotally connected to the frontportion 12 a of the frame element 12 and the upper rail 16. Moreover,the front linking mechanism 20 may include a pair of linking arms thatare pivotally connected to the frame element front portion 12 a and theupper rail 16.

[0046] Second Detailed Representative Embodiment

[0047] The second detailed representative embodiment will now describedwith reference to FIGS. 4 and 5. Because the second embodiment relatesto the first embodiment, only constructions and elements that aredifferent from the first embodiment will be explained in detail.Elements that are the same in the first embodiment will be identified bythe same reference numerals and detailed description of such elementswill be omitted.

[0048] In this embodiment, the seat lifting device may further include apair of drive mechanisms 140 (one of which is shown). Each of the drivemechanisms 140 may preferably includes a drive source assembly thatcomprises a gear box 144 and a motor 142. As best shown in FIG. 5,unlike the first embodiment, the gear box 144 and the motor 142 maypreferably be laterally or horizontally positioned.

[0049] Third Detailed Representative Embodiment

[0050] The third detailed representative embodiment will now describedwith reference to FIG. 6. Because the third embodiment relates to thefirst and second embodiments, only constructions and elements that aredifferent from the first and second embodiments will be explained indetail. Elements that are the same in the first and second embodimentswill be identified by the same reference numerals and detaileddescription of such elements will be omitted.

[0051] In this embodiment, the seat lifting device may further include apair of drive mechanisms 240 (one of which is shown). Each of the drivemechanisms 240 may preferably includes a drive source assembly thatcomprises a gear box 244 and a motor 242. As shown in FIG. 6, unlike thefirst and second embodiments, the motor 242 is separate from the gearbox 244. That is, the motor 242 is positioned in the front portion 12 aof the frame element 12 and fixed thereto. The motor 242 thus positionedis coupled to the gear box 244 via a power transmitting member 243, suchas a rotating cable or a rotating shaft, such that a drive gear (notshown) received in the gear box 244 is driven when the motor 242 isdriven.

[0052] Representative examples of the present teachings have beendescribed in detail with reference to the attached drawings. Thisdetailed description is merely intended to teach a person of skill inthe art further details for practicing preferred aspects of the presentteachings and is not intended to limit the scope of the invention. Onlythe claims define the scope of the claimed invention. Therefore,combinations of features and steps disclosed in the foregoing detaildescription may not be necessary to practice the invention in thebroadest sense, and are instead taught merely to particularly describedetailed representative examples of the invention. Moreover, the variousfeatures taught in this specification may be combined in ways that arenot specifically enumerated in order to obtain additional usefulembodiments of the present teachings.

1. A seat lifting device disposed between a seat support for supportinga seat cushion and a seat mount for mounting the seat support in orderto vertically adjust the seat cushion, comprising: a first linkingmechanism movably interconnecting the seat support and the seat mount,the first linking mechanism comprising first and second linking armsthat are respectively pivotally connected to the seat mount and the seatsupport via pivot axes, wherein one of the pivot axes of the secondlinking arm comprises a movable pivot axis that is arranged andconstructed to move along the second linking arm and to engage thesecond linking arm, so that substantial length of the second linking armcan be changed when the movable pivot axis moves along the secondlinking arm.
 2. A seat lifting device as defined in claim 1, wherein thesecond linking arm comprises a threaded shaft that is pivotallyconnected to the seat mount and the seat support and a gear assemblyhaving a nut that engages the threaded shaft, the gear assembly isarranged and constructed to move along the threaded shaft, and whereinthe movable pivot axis is mechanically connected to the gear assembly,so as to move along the threaded shaft when the gear assembly movesalong the threaded shaft.
 3. A seat lifting device disposed between aseat support for supporting a seat cushion and a seat mount for mountingthe seat support in order to vertically adjust the seat cushion,comprising: a pair of first linking mechanisms movably interconnectingthe seat support and the seat mount, at least one of the first linkingmechanisms comprising first and second linking arms that arerespectively pivotally connected to the seat mount and the seat supportvia pivot axes, wherein one of the pivot axes of the second linking armcomprises a movable pivot axis that is arranged and constructed to movealong the second linking arm and to engage the second linking arm, sothat substantial length of the second linking arm can be changed whenthe movable pivot axis moves along the second linking arm.
 4. A seatlifting device as defined in claim 3, wherein the second linking armcomprises a threaded shaft that is pivotally connected to the seat mountand the seat support and a gear assembly having a nut that engages thethreaded shaft, the gear assembly is arranged and constructed to movealong the threaded shaft, and wherein the movable pivot axis ismechanically connected to the gear assembly, so as to move along thethreaded shaft when the gear assembly moves along the threaded shaft. 5.A seat lifting device as defined in claim 4 further comprising a secondlinking mechanism movably interconnecting the seat support and the seatmount, wherein the second linking mechanism comprises an elongated guideslot formed in the seat mount and a guide pin attached to the seatsupport, and wherein the guide pin slidably engages the guide slot.
 6. Aseat lifting device as defined in claim 2 further comprising anactuator, wherein the actuator is arranged and constructed to drive thegear assembly, thereby moving the gear assembly and the movable pivotaxis attached thereto along the threaded shaft.
 7. A seat lifting deviceas defined in claim 4 further comprising an actuator, wherein theactuator is arranged and constructed to drive the gear assembly, therebymoving the gear assembly and the movable pivot axis attached theretoalong the threaded shaft.
 8. A seat lifting device as defined in claim 5further comprising an actuator, wherein the actuator is arranged andconstructed to drive the gear assembly, thereby moving the gear assemblyand the movable pivot axis attached thereto along the threaded shaft. 9.A seat lifting device disposed between a seat support for supporting aseat cushion and a seat mount for mounting the seat support in order tovertically adjust the seat cushion, comprising: a pair of first linkingmechanisms movably interconnecting the seat support and the seat mount,at least one of the first linking mechanisms comprising first and secondlinking arms that are respectively pivotally connected to the seat mountand the seat support via pivot axes; and a second linking mechanismmovably interconnecting the seat support and the seat mount, the secondlinking mechanism comprising an elongated guide slot formed in the seatmount and a guide pin attached to the seat support, the guide pinslidably engaging the guide slot, wherein one of the pivot axes of thesecond linking arm comprises a movable pivot axis that is arranged andconstructed to move along the second linking arm and to engage thesecond linking arm, so that substantial length of the second linking armcan be changed when the movable pivot axis moves along the secondlinking arm, wherein the second linking arm comprises a threaded shaftthat is pivotally connected to the seat mount and the seat support and agear assembly having a nut that engages the threaded shaft, the gearassembly is arranged and constructed to move along the threaded shaft,and wherein the movable pivot axis is mechanically connected to the gearassembly, so as to move along the threaded shaft when the gear assemblymoves along the threaded shaft.
 10. A seat lifting device as defined inclaim 1, wherein the first and second linking arms are connected to theseat support via a common pivot axis, and wherein the first and secondlinking arms are respectively connected to the seat mount via first andsecond pivot axes, the second pivot axis is positioned behind the firstpivot axis.
 11. A seat lifting device as defined in claim 3, wherein thefirst and second linking arms are connected to the seat support via acommon pivot axis, and wherein the first and second linking arms arerespectively connected to the seat mount via first and second pivotaxes, the second pivot axis is positioned behind the first pivot axis.12. A seat lifting device as defined in claim 9, wherein the first andsecond linking arms are connected to the seat support via a common pivotaxis, and wherein the first and second linking arms are respectivelyconnected to the seat mount via first and second pivot axes, the secondpivot axis is positioned behind the first pivot axis.
 13. A seat liftingdevice as defined in claim 2, wherein the first linking mechanism ispositioned adjacent to a seatbelt connecting position on the seatsupport.
 14. A seat lifting device as defined in claim 4, wherein thefirst linking mechanism is positioned adjacent to a seatbelt connectingposition on the seat support.
 15. A seat lifting device as defined inclaim 5, wherein the first linking mechanism is positioned adjacent to aseatbelt connecting position on the seat support.
 16. A seat liftingdevice as defined in claim 9, wherein the first linking mechanism ispositioned adjacent to a seatbelt connecting position on the seatsupport.